Modern day integrated chips used in wireless communication devices (e.g., for mobile phones) comprise receiver chains that are configured to receive incoming signals from an antenna, amplify the received incoming signals, and demodulate the amplified incoming signals without reducing the quality of the signals (e.g., through the addition of undesired noise to the received signals).
Demodulation of an incoming signal may be performed using a mixer that receives a high radio frequency (RF) signal, performs frequency conversion of the signal from the RF frequency to a lower intermediate frequency (IF), and outputs the lower IF frequency signal to circuit components configured to perform further processing (e.g., filtering). The quality and performance of a wireless communication device depends to a large extent on the mixer's conversion gain (e.g., ratio of output signal amplitude to input signal amplitude) and signal-to-noise ratio. Ideally, demodulation is performed with a low degradation of signal-to-noise ratio and a high conversion gain. Therefore, active mixers with active preamplifiers and passive switching stages are often used in wireless communication applications since they allow for an improved signal-to-noise ratio (e.g., to decrease deterioration of noise) compared to the purely passive mixers, thereby improving reception sensitivity of a receiver.